A study of the Newkirk effect in turbomachinery

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1、A.D.DIMAROGONASLehighuniversity,Betnienem,Perm.(V.S.A.)(ReceivedJanuary29,1974)SUMMARYAnanalyticalandexperimentalstudywasundertakenontheNewkirkEffectasannliedtotnrhomarhinervwhir.hi«ihetvihratinnchanoe.nrodur^Hwhenahiffh•••置"•隹•••••••••••一■■■垂•看••^~~，__一•—••申—擎争，》~•■賺

2、—擎jf—•，賢爭••幸__••—••——•——•speearotorrubsonstationarycomponentsduetotheunevendistributionoftheproducedheataroundtherotor.Theanalysispredictedthreepossiblemodesofthe-Newkirk-Effeetc-spiralling,osciHatoryandconstan卜modes.—Thefirst4s^as-sociatedwithveryhighvibrationamplitu

3、desandthelattertwowithlowamplitudes，evenvibrationsuppressionandmaybeconsideredasstablemodes.…TosupportandveriTyanalystanexpenrhehtaV^wascoristrucfedandalimitednumberoftestsconducted.Thetestresultsverifiedbothquantitativelyandqualitativelytheanalyticalfindingsforthemod

4、esoftheNewkirkEffect.Theparameterstudyindicatedthatstabilityofthesystemdoesnotdependexplicitlyonwhethertherunningspeedisbeloworabovethecriticalspeed，butratheronthephaseanglebetweenstaticanddynamicbow.Thisisadynamicpropertyofthesystemunrelatedtothefrictioncharacteristi

5、cs.Itdepends,toalesserextent,upontheamountofgeneratedheatandtheothercharacteristicsofthesystem.Theclearance-was-foundto-beaveryimportantfactor.Theexistenceofa-thresholdvalueoftheclearancewasdemonstrated.INTRODUCTIONOneofthemainobjectivesinthedesignofmodernmachinesisth

6、ereductionofweightandimprovementinquality.Thisimprovementhasintroducedhighrotatingspeeds,velocities,deflectionsandflexibilitiesofthemacmne’smembers,anddesignersarenowfacingnewproblemsnotalwaysconsideredbefore.Thedirectionofdesigningover-tunedrotatingmembers，i.e.,witht

7、heoperatingspeedlowerthanthefirsteritiealspeed,-isno-'i&Rger-followedT-Modernmachinesoperateabovethefirstcriticalspeedandveryoftenabovethesecondorthird.Thesupportsandfoundationsbecomeflexible，too,andtheirnaturalfrequencies'interferesometimeswiththeoperaring^speeds.Th

8、eamjrffficraikmfactor合becomelower，buttherearestartingproblemswhenpassingthroughthecriticalspeeds.Tooringtheunbalanceresponse